Modern lubricants find use in a wide variety of applications. Lubricants can have various functions, including controlling friction between surfaces of moving parts, reducing wear of moving parts, reducing corrosion of surfaces of moving parts, particularly metal surfaces, damping mechanical shock in gears, and forming a seal on the walls of engine cylinders. A lubricant composition contains a base oil and typically one or more additives or modifiers that provide additional performance properties to the lubricant composition.
Soot or sludge formation is a widely encountered problem with many lubricants, particularly those that are used in fuel burning engines, such as automotive engines, marine engines, railroad engines, power plant diesels, and the like. Soot is formed from incomplete combustion in engine and exhaust systems. Soot particles can lead to an increase in the viscosity of the lubricant, deposition of contaminants onto metal surfaces, and soot induced wear. Thus, control of soot is an important performance attribute for lubricants used in fuel burning engines.
Soot control may generally be provided through inclusion of dispersants, detergents, or both in the lubricant. Dispersants suspend soot and similar contaminants in the bulk oil, thereby preventing an increase in engine oil (lubricant) viscosity. Detergents are primarily designed to neutralize combustion products; through neutralization of those species, detergents inhibit rust and corrosion and high temperature deposits.
Conventional dispersants and detergents are often lacking for a number of reasons, including the inability to provide the desired performance properties, processing problems, overall performance per cost, or the inability to optimize properties based on specific end-use performance characteristics. For example, viscometrics and low temperature properties are important variables in the final product and dispersants and detergents with broader flexibility offer processing advantages to the formulator. Additionally, many dispersants were developed for hydrocarbon based lubricants and show incompatibility with polyalkylene glycol base oils due to their low solubility in polyalkylene glycols.
The problem addressed by this invention is the provision of new compositions that are useful as dispersants and/or detergent additives for engine lubricants.